Definition of "Isa"

Isa¹

proper noun
1. A diminutive of the female given name Isabel or of its variant forms, sometimes also used as a formal given name.
  Quotations
  Even "Liz" brought little to his memory; though he said: "The name does recall the fact of a sister. But why call her Isa?" "Just as easy as Liz, or any of the lot, Eliza, Elizabeth, Betsy and Bess. Isa, that's, I think, a sort of a city name," Lee said, with a shadow of a smile.
  1885, Arthur's Home Magazine, volume 53, page 165
  It's an awkward name: Isamay, pronounced Is-a-may. Isa is my paternal grandmother's name (shortened from Isabel) and May my maternal grandmother's (it comes, somehow, from Margaret). The amalgamation is, as you see, strictly alphabetical. Life, I feel, would have been much easier if they had chosen Maybel.
  2010, Margaret Forster, Isa & May, Chatto & Windus, page 5

Isa²

proper noun
1. A male given name from Arabic mainly used by Muslims.